Today, a user can receive a communication over a plurality of terminals associated with one and the same shared public identity (IMPU for IP Multimedia Public Identity in English) or one and the same telephone number. When a call intended for the shared public identity is issued, the call request is transmitted to the plurality of terminals and a user of a terminal in the plurality of terminals can accept the call from his terminal.
The drawback of this technique is that the user issuing the communication does not know that the communication can be taken by any terminal in a plurality of terminals and therefore does not know that several users are liable to reply to him.
Moreover, the calling user does not know the state of the terminals in the plurality of terminals liable to receive the communication. The term “state of a terminal” specifically refers here to the state of presence of a terminal on the communication network, the fact that the terminal is or is not registered in the communication network, or whether the terminal is on a call, engaged, unreachable or unavailable.
Document WO2012089954 allows a first terminal registered in a communication network and associated with a shared public identity to obtain an item of information on the presence and the state of a second terminal registered in the communication network and associated with the same shared public identity as the first terminal. A user of the first terminal is thus informed as to whether a second terminal associated with the same shared public identity is registered in the communication network, whether it is in a nomadic situation, whether it is engaged, etc.
Thus, on reception of a communication request intended for the public identity shared by the first and the second terminal, the user of the first terminal can decide whether or not to use the first terminal to reply to the communication request according to the state of the second terminal.
This solution does not make it possible to inform the calling terminal of the state of the called terminals because only the terminals associated with the same shared public identity are notified of the state of the first and second called terminals.
Moreover, adapting this solution so that the calling terminal is informed of the state of the first and second called terminals would require excessive complexity. This is because it is impossible to predict in advance either the shared public identity to which the calling terminal will issue a communication or the moment of issue of such a communication. It would then be necessary to permanently save in the communication network the state of all the terminals registered in the communication network that are liable to be called in order to inform the calling terminal of the state of the terminals liable to be called when the calling terminal issues a communication to the shared public identity. This solution cannot be considered because it would require very large memory resources.